(1) Field of the Invention
This invention relates, broadly speaking, to a safety device for vehicles.
More particularly, this invention relates to an improved air bag device for a vehicle, which device can rapidly be deployed by inflation in the event of a collision to prevent or reduce the extent of injury to an occupant of the vehicle.
(2) Description of the Prior Art
Air bag devices for vehicles are known. Such air bag devices have in the past been based upon the ignition of a quantity of rapidly combustible material, particularly sodium azide, triggered by a collision sensor on the vehicle, to rapidly generate combustion gases in sufficient quantity to inflate the air bag which then acts as a cushion to protect the occupant of the vehicle from injury which otherwise could result from the occupant coming into violent contact with the steering wheel or dashboard of the vehicle. Although these prior art air bag devices have been instrumental in reducing the number of fatalities or serious injuries, they have a number of shortcomings, among which are the generation of high temperature combustion gases of approximately 300.degree. F. which when vented have caused serious burns on the body of the occupant, and the problem of disposing of the environment-unfriendly combustible sodium azide in the event, more probable than not, that the vehicle is brought to an automobile junkyard without the air bag device having been deployed as the result of a collision. So dangerous is the sodium azide that government regulations require that it be ignited before automobile junkyards can accept or retain the vehicle.
A notable improvement in air bag devices is described in copending U.S. patent application Ser. No. 07/741,304 filed on Aug. 7, 1991 in the names of Larry D. Hoagland and Stephen J. Brockman, now U.S. Pat. No. 5,152,550, entitled "Air Bag Device for Vehicles," and assigned to the assignee of the present application. Such improvement in air bag devices, as disclosed in the said copending patent application, employs, among other things:
(a) a reservoir containing prior to collision a pressurized fluid and having an outlet, PA0 (b) an inflatable cushion having an inlet and being inflated solely by the pressurized fluid in the reservoir in the event of a collision, PA0 (c) a frangible plate interposed between the outlet of the reservoir and the inlet of the inflatable cushion and preventing the passage of pressurized fluid from the reservoir to the interior of the inflatable cushion, the frangible plate having an upstream side facing the outlet of the reservoir and a downstream side, the frangible plate being brittle and shattering into discrete fragments when struck, PA0 (d) a striking member adjacent the downstream side of the frangible plate and having a first end to strike the downstream side of the frangible plate to rapidly shatter the frangible plate, and a second end opposite the first end, PA0 and (e) means to rapidly apply a force to the second end of the striking member in response to a signal of a collision, to drive the striking member toward the downstream side of the frangible plate so that the first end of the striking member shatters the frangible plate, PA0 (f) whereupon pressurized fluid escapes from the reservoir and inflates the cushion.